DR0:\1ILITES. 29 



identical in the fossil and recent forms, and they constitute, in both, the obvious means of 

 attachment of the hairy clothing. 



It differs from Dromia in the shape of the carapace, which in Dromilites is nearly 

 orbicular, or rather broader posteriorly, whOst in Dromia it becomes abruptly narrowed 

 from the latero-anterior margin backwards. The surface is more nodulated than in the 

 recent form, and the marginal inequalities and projections are very chfferent. The 

 abdomen is much less broad in each sex. But the most remarkable distinction consists in 

 the existence of the broad rugose posterior portion of the branchial region, which is 

 strikingly dissimilar from the anterior portion, and chstinctly separated from it. It will be 

 seen in the description of D. LamarcJcii, that this peculiarity is, in that species, carried to 

 an extreme, and that this singular structure extends quite across the carapace, occupying 

 continuously nearly its posterior half. Professor IM'Coy states in one part of his 

 description of Basinofopus Lamarckii, that this rugose area is situated behind all the other 

 regions of the body. It consists, however, undoubtedly, of only the metabranchial lobes, 

 which are developed to an extraordinary extent. 



Dromilites Lasiarckii. Plate V, figs. 1 — 9. 



Testa rugoso-scabra, paulo longiore quam latiore, regione cardiaca bituberculata. 



Inachus Lamarckii, Besmarest. Crust, foss., t. ix, figs. 15, 16, p. 116. 

 Basinotopus Lamaeckii, M'Coy. Ann. Nat. Hist., 1849, p. 168. 



Bescr. Carapace everywhere rugose, and almost scabrous, a little longer than it 

 is broad, moderately convex, in the male subdepressed ; front with a short, triangular 

 rostrum, somewhat inflected and channeled, \\Ai\\ a small tooth above on each side, and a 

 tubercle forming the inner angle of the orbit, another at its outer angle, the upper edge of 

 the orbit slightly elevated ; lateral margin with five rather long spines, including the extra- 

 orbital, the fifth being rather more distant from the fourth than the anterior ones from 

 each other ; gastric region occupying nearly half the length of the carapace, tuberculated. 

 The epi- and proto-gastric lobes with three tubercles on each side, foiToing a line which 

 diverges backwards, thus bordering a triansrlc fonned bv the union of the mesocrastric and 

 metagastric, which extends forwards to the base of the rostrum ; the mesogastric with 

 several small tubercles, and the metagastric with two larger ones ; the urogastric forming 

 a narrow, transverse ridge, which extends laterally the whole breadth of the cardiac region ; 

 the latter is prominent, and has two strong tubercles in its anterior lobe, and the posterior 

 is scarcely distinguishable from it, and becomes blended with the nigose portion of 

 the branchial region ; hepatic region small, circumscribed at its margin by the two 

 anterior marginal spines, and bearing one or two small tubercles. The branchial regions 

 very large, each divided transversely by a broad sulcus, and a prominent ridge extending 



